At a Glance: Microsoft CEO Ballmer's ups and downs

The Associated Press, None

Microsoft CEO Steve Ballmer announced on Friday that he plans to retire from the world's biggest software company after more than 13 years at its helm. Here's a look at the ups and downs of his tenure:

- 1980: Ballmer joins the company co-founded by Bill Gates and Paul Allen in 1975.

- July 21, 1998: Widely seen as the successor to chairman and longtime friend Gates, Ballmer is named president of the software company. He'd previously led Microsoft's sales and marketing.

- Sept. 23, 1999: Ballmer warns that technology stocks are overvalued, including those of his own company, in public remarks that help accelerate a sharp sell-off on Wall Street. He blames a "gold rush" mentality for the stock price increases.

- Jan. 13, 2000: Gates promotes Ballmer to CEO of Microsoft while staying on as chairman and chief software architect.

- Nov. 15, 2001: Microsoft releases its Xbox video game system, one of the company's most successful products.

- March 26, 2004: At a conference for online advertisers, Ballmer says Microsoft's biggest mistake was failing to develop its own search engine, which caused it to fall behind rivals Google and Yahoo in the space. "That's probably the thing I feel worst about over the last few years," says Ballmer. Ballmer vows to put more money into research and development of search technology at Microsoft.